Railroad ballast cleaning machinery is well known in the art. These machines take up the ballast from the track bed, clean the ballast, return the cleaned material to the track, and discard the "dirt" or waste contaminating material. One reason for cleaning the ballast is to provide cleaner ballast which can drain water away from the railroad cross ties in order to ensure a longer "life" for the ties. Over a period of time, the track bed becomes contaminated by mud working its way up from underneath, by dirt getting into the ballast from the top, or by the ballast being slowly ground into small particles by vibration caused as trains pass over the ballast. The ballast becomes so contaminated after a period of time that moisture is held around the ties, thus resulting in deterioration of the ties, which results in expensive tie replacement becoming necessary. Thus, periodic ballast cleaning is necessary to ensure good drainage. A further disadvantage of contaminated ballast is that the track tends to settle in muddy spots, thus destroying the alignment (line) and surface of the rails.
Some types of ballast cleaners are disclosed in U.S. Pat. Nos. 4,705,115, issued on Nov. 10, 1985, to John B. Whitaker, Jr.; 4,850,123, issued on Jul. 25, 1989, to John B. Whitaker, Jr.; 4,534,415, issued on Aug. 13, 1985, to Josef Theurer; and 4,813,488, issued on Mar. 31, 1989, to Josef Theurer. Typically, there are two types of ballast cleaners. One type simply takes up the ballast along the track shoulders (outside the ends of the cross ties) and is known as a "shoulder cleaner." The second type takes up the material underneath and between the cross ties and is known as an "undercutter cleaner."
Normally, a shoulder cleaner utilizes a rotating "ditcher wheel" on each side to take the ballast up from the track shoulder while an undercutter uses a continuous cutter chain to pull the material from underneath the track.
One type of chain design (U.S. Pat. No. 4,813,488, issued to Josef Theurer and assigned to Franz Plasser, Vienna, Austria) is such that it picks up the material on the shoulder along with the under-track material. After the material is picked up, it is carried to a single cleaning station comprised of a pair of vibrating cleaning screens. The vibrating screens shake the contaminants from the ballast and separates the larger pieces of ballast from the unwanted smaller pieces of contaminants. A common outlet is provided to return the cleaned ballast to the track bed. The waste material is conveyed from the screen to the side of the track or it is loaded onto a hopper car. The speed of the operation of this apparatus is limited by the provision of a single outlet common to the two cleaning screens which control the rate of flow of the cleaned ballast back to the track.
Furthermore, the apparatus of U.S. Pat. No. 4,813,488 requires the use of an undercutter chain under the tracks and that the tracks be raised so that the chain can be installed in a passageway which must be dug out from under the tracks. After the ballast cleaning operation is completed, the tracks must be levelled in an attempt to restore the original track line.
U.S. Pat. No. 4,534,415, issued to Josef Theurer and assigned to Franz Plasser, Vienna, Austria, is directed to a ballast cleaning machine with two ballast screening installations. While this patent discloses the provision of two screens for cleaning the ballast, it should be noted that this apparatus also uses a single excavating mechanism (undercutter chain) which limits the forward speed of the apparatus for reasons explained supra, in conjunction with U.S. Pat. No. 4,813,488. Additionally, the speed of operation is limited to the speed of operation and the size of the conveyor belts which are used to redistribute the cleaned ballast back to the track bed.
In U.S. Pat. Nos. 4,705,115 and 4,850,123, a single vibrating screen (cleaning station) is used in conjunction with a single ditcher wheel or, in the case of U.S. Pat. No. 4,705,115, an apparatus which has two ditcher wheels, one wheel on each side of the frame. However, since only one screen is used in conjunction with the ditcher wheel (or wheels), the speed of the apparatus is limited to the speed at which the ballast can be cleaned at the single cleaning station. An additional drawback of U.S. Pat. No. 4,705,115 is that only the portion of the ballast under the tracks is cleaned in a single operation, while the excavated shoulder ballast is returned uncleaned to the center of the track. Such procedure requires more frequent periodic cleaning operations.
Apparatus of the present invention overcomes the above-noted drawbacks and inadequacies by providing a ballast reconditioning system having a pair of excavating ditcher wheels with each ditcher wheel being placed on opposite sides of a supporting frame. Each ditcher wheel includes a plurality of annularly arranged buckets which pick up the ballast and empties the ballast that is picked up by the buckets onto a discrete corresponding cleaning station, thus resulting in a ballast cleaning system which cleans the ballast at generally twice the speed that any of the prior art patents can accomplish. An excavating member is also mounted to the vehicle frame behind each ditcher wheel to remove ballast from beneath the cross ties.